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Public proof of conceptAwaiting NVD analysis

CVE-2026-49990

BACnet Stack: AtomicReadFile/AtomicWriteFile stream fileStartPosition validation flaw causes out-of-bounds read/write in RAM file backends

A public proof of concept exists; no exploitation attested.

  • Published2026-11-13
  • WeaknessCWE-125 · CWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. From versions 1.4.2 to before 1.4.5, and 1.5.0 to before 1.5.1, a signed fileStartPosition taken from AtomicReadFile and AtomicWriteFile stream-access requests is not validated tightly enough before it reaches the RAM file backends. Practical impact includes: reliable denial of service via process crash, out-of-bounds read that may expose adjacent memory contents, or out-of-bounds write that may corrupt heap memory and destabilize the process. This issue has been patched in versions 1.4.5 and 1.5.1.

Timeline

dates in UTC
  1. 2026-11-1315:54CVE publishedCNA

Versions per branch

Products declared by the CNA

As GitHub_M, the CNA that assigned this CVE, declared them in the CVE record; versions as written. NVD lists no product for this CVE yet: this is the only product data so far.

  • bacnet-stack
    Affected
    • = >= 1.4.2, < 1.4.5no fix stated
    • = >= 1.5.0, < 1.5.1no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-13

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-49990 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CISA-ADPSSVC decisionpoc2026-11-13
  • CNACVSS 3.18.62026-11-13
  • CNAweakness (CWE)CWE-125, CWE-7872026-11-13
  • NVDweakness (CWE)CWE-125, CWE-787read 2026-11-13

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
Published
2026-11-13
Last Modified
2026-11-13
NVD status
Awaiting Analysis

Frequently asked questions

What is CVE-2026-49990?

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. From versions 1.4.2 to before 1.4.5, and 1.5.0 to before 1.5.1, a signed fileStartPosition taken from AtomicReadFile and AtomicWriteFile stream-access requests is not validated tightly enough before it reaches the RAM file backends. Practical impact includes: reliable denial of service via process crash, out-of-bounds read that may expose adjacent memory contents, or out-of-bounds write that may corrupt heap memory and destabilize the process. This issue has been patched in versions 1.4.5 and 1.5.1.

Is CVE-2026-49990 actively exploited?

A proof-of-concept exploit exists for CVE-2026-49990, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-49990?

CVE-2026-49990 has a CVSS v3 base score of 8.6 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H.

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